Conditional Auto increment in xsl

Question

I have an XML some thing like

<V>
  <W>
    <X>1</X> 
  </W>
  <W>
    <Y>1</Y> 
  </W>
  <W>
    <X>1555</X> 
  </W>
  <W>
    <X>1</X> 
  </W>
</V>

i want to make it something like this

<entity ID="start">
    <f ID="NewField">0001</f>
    <f ID="NewField">0001</f>
    <f ID="NewField">0002</f>
    <f ID="NewField">0003</f>
</entity>

When the field is V/W/X then NewField should be incremented by 1 as many times the tag V/W/X is found. Similarly for V/W/Y.

The Xsl which i am using is

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"&gt;
<xsl:template match="/">
<entity ID="start">
    <xsl:for-each select="V/W">
     <xsl:if test="X">
      <xsl:variable name="my_var">
       <xsl:value-of select="concat('000',position())"/>
      </xsl:variable>
      <f ID="NewField"><xsl:value-of  select="$my_var"/></f>
     </xsl:if>
     <xsl:if test="Y">
      <xsl:variable name="my_var">
       <xsl:value-of select="concat('000',position())"/>
      </xsl:variable>
      <f ID="NewField"><xsl:value-of  select="$my_var"/></f>
     </xsl:if>
    </xsl:for-each>
</entity>
</xsl:template>
</xsl:stylesheet>

but is gives me wrong result , something like this

<entity ID="start">
  <f ID="NewField">0001</f>
  <f ID="NewField">0002</f> 
  <f ID="NewField">0003</f> 
  <f ID="NewField">0004</f> 
</entity>

Answer 1

I think you're looking for something like count(preceding::X) expression. Of course you may want to make it more complex and then take care about number formatting, but that sounds like a starting point you're looking for.

Answer 2

<xsl:stylesheet 
  version="1.0" 
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
>
  <xsl:template match="V">
    <entity ID="start">
      <xsl:apply-templates select="W/X|W/Y" />
    </entity>
  </xsl:template>

  <xsl:template match="X|Y">
    <f ID="NewField">
      <xsl:variable name="counter" select="
        count(
          parent::W/preceding-sibling::W/*[name() = name(current())]
        ) + 1
      " />
      <xsl:value-of select="format-number($counter, '0000')" />
    </f>
  </xsl:template>

</xsl:stylesheet>

This:

parent::W/preceding-sibling::W/*[name() = name(current())]

selects all preceding elements of the same name as the current element. E.g., if the point of execution is on this node:

<X>1555</X>

It goes one level up (parent::W), then selects all preceding <W> siblings, and of those it selects any child (*) that has a name of X - since X is the name of the current() element.

The resulting node-set is counted and incremented by one. format-number() is used to generate a nice clean output:

<entity ID="start">
  <f ID="NewField">0001</f>
  <f ID="NewField">0001</f>
  <f ID="NewField">0002</f>
  <f ID="NewField">0003</f>
</entity>

Answer 3

If you want to number nodes with XSLT then the xsl:number element can help:

<xsl:stylesheet
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  version="1.0">

  <xsl:output indent="yes"/>

  <xsl:template match="/">
    <entity ID="start">
      <xsl:apply-templates select="descendant::X | descendant::Y"/>
    </entity>
  </xsl:template>

  <xsl:template match="X | Y">
    <f ID="NewField"><xsl:number level="any" format="0000"/></f>
  </xsl:template>

</xsl:stylesheet>